The present invention relates generally to diagnostic systems for fuel injected engines and, more particularly, to an apparatus and method to adjust the fuel quantity delivered to each cylinder of a fuel injected engine.
Fuel injected engines inject a known quantity of fuel into each cylinder during engine operation based on engine speed, load, engine temperature, air temperature, barometric pressure, and other measurable parameters. This known quantity of fuel is determined for each engine operating point by technicians skilled in the art of internal combustion engines and design, and is a sufficient quantity to cause the engine to run well at each operating point despite numerous manufacturing tolerances that may be encountered. If the engine is not functioning properly, it could be that the wrong quantity of fuel is being delivered to one or more of the cylinders due to a malfunctioning component. It could also be the case that for some other unknown malfunctioning component, the engine requires more or less fuel at a given operating point than a properly functioning engine. While this is not catastrophic, if operated over time with an insufficient amount of fuel being delivered to the engine cylinders, excessive wear and/or breakdown of the engine can occur.
When an engine is not functioning properly, it is most often brought to a knowledgeable and skilled technician for diagnosis and repair. It is often very helpful in the diagnosis of a malfunctioning engine to know if one or more of the engine cylinders is not receiving the desired quantity of fuel. Unlike a carbureted engine, there are no screws in a fuel injected engine for the technician to use to adjust the air/fuel mixture that is delivered to each cylinder. At present, there are no tools which allow technicians to make adjustments to the fuel quantity of a fuel injected engine. Thus, it is very difficult to determine whether the quantity of fuel each cylinder is receiving is the correct amount.
The present invention is for use in an unique diagnostic system for fuel injected engines. Such a system must allow a technician to temporarily adjust the quantity of fuel delivered to each cylinder of the engine. However, it is important to maintain only a temporary change in fuel delivery as a permanent change could violate EPA emission guidelines. It is also important for a technician to be able to precisely adjust the amount of fuel being delivered to the engine cylinder.
It would therefore be advantageous to have a diagnostic system that allows for temporary adjustment of the fuel quantity being delivered to a fuel injected engine.
The present invention provides a system for adjusting the fuel quantity delivered to each cylinder of a fuel injected engine. The present invention also provides a means for increasing or decreasing the on-time of a fuel injector of the engine. Further, the present invention provides for storing any change in the operating parameters in the internal memory of the engine""s electronic control unit (ECU). All of which overcome the aforementioned shortcomings.
In accordance with one aspect of the invention, a diagnostic system is provided for use with a fuel injected engine. A service computer is connected to an engine control unit of the fuel injected engine. The service computer has a computer readable storage medium having thereon a computer program that when executed receives operating data of the fuel injected engine from the engine""s ECU. The ECU receives the operating data from a plurality of sensors connected thereto. The plurality of sensors provide operating data of the fuel injected engine including engine speed, load, engine temperature, air temperature, and barometric pressure. The ECU is further connected to a plurality of engine components including a number of fuel injectors. Upon receipt of data from the service computer, the ECU alters the fuel quantity being delivered to the fuel injected engine.
In accordance with another aspect of the invention, a diagnostic machine for use with a fuel injected engine of an outboard motor is provided. The diagnostic machine includes a communications interface connectable to an ECU of a fuel injected engine. The communications interface transmits fuel injector data from the ECU to a processor. The processor is connected to a computer readable storage medium of the diagnostic machine having thereon a computer program that when executed causes the processor to determine an adjustment to fuel injector firing time and further transmit that adjustment to the ECU.
In accordance with yet another aspect of the invention, a method to adjust fuel quantity being delivered to a fuel injected engine is disclosed. The method includes the steps of connecting a diagnostic machine to an ECU of a fuel injected engine. Fuel injector data of the fuel injected engine is then transmitted from the ECU to the diagnostic machine. Next, the method selects at least one engine fuel injector controlled by a control signal having a corresponding pulse width. The method next modifies the injector pulse width based upon at least one user input wherein modification of the injector pulse width results in an adjustment to the fuel quantity being delivered to the fuel injector. The method then transmits the modified injector pulse width of the fuel injector to the ECU of the fuel injected engine where, ultimately, the modified injector pulse width is stored in memory of the ECU.
Another aspect of the present invention provides a system and method for adjusting the fuel quantity being delivered to a fuel injected engine of an outboard marine motor. The method includes the steps of receiving operating parameters of a fuel injected engine, determining the fuel flow of at least one fuel injector based on the operating parameters of the fuel injected engine, modifying the fuel flow of the fuel injector thereby temporarily adjusting the amount of fuel being delivered to the fuel injected engine.
Various other features, objects and advantages of the present invention will be made apparent from the following detailed description and the drawings.